Patent GB-347618-A (GB)
Title: Improvements in process and apparatus for removing solid particles from liquids
IPC: B01D21/24
Filed: 1929-12-23
Abstract: 347,618. Gravity-separation apparatus. DORR CO., 247, Park Avenue, New York, U.S.A. Dec. 23, 1929, No. 39299. Convention date, Dec. 24, 1928. [Class 111.] Heavier solid matter is allowed to separate from liquid in a settling chamber and discharged therefrom into a second compartment in which any lighter matter associated with the heavy matter is brought into suspension so that it can overflow and return with liquid to the settling chamber. The process is applicable in the treatment of sewage for the separation of grit free from solid organic matter. A double system of tanks suitable for the treatment of sewage is shown in plan in Fig 1. The liquid passes from a sewer 21 through an inflow channel 22, and openings 23, controlled by adjustable vertical vanes 24, Fig. 9, into a settling-tank 20. The liquid freed from grit flows away over a weir 26 into an outflow passage 27 leading to a sewer 28. A byepass channel 29 is provided. The tank 20 is provided with mechanism as described in Specification 349,473 for collecting solid matter. The settled grit with some associated organic matter is pushed towards the periphery by rakes 35 suspended from arms 32 mounted on a framework 33 which rotates on a central pillar 34. The grit is collected by scoops 36 at the ends of the arms 32 and discharged down a shoot 57 into a compartment 55. The matter settling in the corners of the tank is collected by a scoop suspended from a frame 37 the inner end of which slides relatively to the frame 33 and serves to rotate the latter. The outer end of the frame 37 is supported by a carriage with a wheel driven by gearing from a motor 40 on the carriage and engaging a track 38 which surrounds the tank. The compartment 55 may, as shown in Fig. 2, be provided with a sloping bottom 56 up which the grit is moved by reciprocating blades or rakes 58, which also by causing agitation remove organic matter from the grit and bring it into suspension so that it flows off at the side for return to the settling-tank 20. The rakes are mounted on channels 59 suspended by hanger plates 60 from levers 62, 63, which are periodically turned to lift the rakes for the floor 56 by means of a cam on a drive shaft 67. The rakes are also reciprocated by means of a crank on the shaft 67 and hangers connected thereto. The rake support includes a horizontal portion with suitably lengthened tines connected by a vertical portion to the lower inclined portion, the arrangement being such that any parts moving up-anddown through the surface of the liquid are nearly at a right-angle to the surface, so that solid matter does not collect upon them. A spray pipe 74, which can be rotatably adjusted to deliver wash water upon the grit as it emerges from the liquid, is provided. The liquid flowing off at the side may enter the settling-tank directly, the compartment being open to the tank, as shown in Fig. 2, save for a supporting pillar 77. When the requisite slope of the base does not allow of this, an arrangement as shown in Fig. 9 may be adopted, the liquid flowing over a discharge deck 79, extending between the highest and lowest liquid levels, and thence through a passage 80 with an outlet 82 into the settling-tank 20. Weir boards 85, Fig. 7, or a partition 87 with openings 88, Fig. 8, may be fitted into slots 86.